Steddi, Go! - simple tube D.I.

[havnjero]

well I've done a few measurements here, with a 1957 RCA 5751.

with a straight cable, for reference:


steddi plugged in, bypassed:


steddi engaged, with 1uF


steddi engaged, with 10uF


and here is the frequency curve trace, with a cable above and steddi below, engaged, with 10 and 1 uF, separately.



I'm not seeing much effect of changing caps @C2, so I'm wondering if changing C1 would be better -- or someplace else?

 

[Tassieviking]

What are you trying to do ?
C1 and the volume pot makes a HPF at 0.2Hz so that is as low as you would ever want it.
I have no idea how to work out the HPF of C2 but usually we use a higher capacitance for a lower frequency, C2 is marked as 47uF in the build docs.

 

[havnjero]

What are you trying to do ?
C1 and the volume pot makes a HPF at 0.2Hz so that is as low as you would ever want it.
I have no idea how to work out the HPF of C2 but usually we use a higher capacitance for a lower frequency, C2 is marked as 47uF in the build docs.

same as before, I'm trying to have a hpf which is not so gradual, so as to include good things in the 50hz region.

 

[havnjero]

same as before, I'm trying to have a hpf which is not so gradual, so as to include good things in the 50hz region.

well, I got around to fiddling with info and doing a slow tone sweep, and found that looking at distortion was good fun.
I also did spl measurements with different tubes, but there was more information with the distortion charts.

I'm using Room Eq Wizard, which is easy to use and colorful. it helps one see what harmonic content looks like at different gain levels. I've been testing mostly at 100mV, which is less than a typical full output of a passive bass guitar like a P bass.

with higher gain tubes, the overall gain goes way down, and with lower gain tubes, the overall gain goes up. sometimes close to 12dbfs. which is a lot.

it sounds great, and is very musical. hard to beat a 12bh7 or clear top rca ecc82.





I find that the tube boards and right angle connectors are not ideal for lots of tube swapping, and the pcb material bends a lot, ruining the solder joint, so I have to go over the joint after changing tubes. it could help for the steddi to have a shoulder for the tube to rest on, which would be more stable in the long run. more like the firebox: